The rankings evaluate 500 gold medal public schools from the 2013 Best High Schools rankings, using Advanced Placement STEM test data for 2011 graduates as the benchmark. Of those schools, 250 earned a numerical rank for their STEM achievement.

Chicago Public Schools said that 663 employees at schools the district is closing, including teachers, teaching assistants and bus aides, don't qualify to follow students to their new schools and will be laid off.

Superintendent Samuel King is rapidly moving forward with an ambitious plan to transform the school division by converting 10 existing schools into public charters and creating an open campus high school.

The preschoolers who arrived at school early for free breakfast on a recent morning quietly ate granola bars and yogurt as middle school students recited part of the rosary over the public address system.